1. Field of the Invention
The present invention generally relates to head assemblies, disk units, and bonding methods and apparatuses, and more particularly to a head assembly which is provided with a so-called head IC (Integrated Circuit) chip, a disk unit which uses such a head assembly, and a bonding method and a bonding apparatus which are suited for producing the head assembly and the disk unit. The present invention also relates to semiconductor parts suited for use in head assemblies, and methods of producing such semiconductor parts.
A hard disk unit is made up of a housing which has a sealed structure. The inside of the housing generally includes a hard disk which rotates at a high speed, and a head assembly which is provided on a tip end of an arm which is driven by an actuator. The head assembly has a head slider and a head IC chip which are mounted on a suspension. The head slider includes a magnetic head which is formed by the thin film technology. The magnetic head includes an inductive head and a magneto-resistive head. The head slider floats from the hard disk which rotates at the high speed, by a distance of the sub-μm order. The inductive head is used to write information on the hard disk, and the magneto-resistive head is used to read the information recorded on the hard disk. The head IC chip has functions of processing inputs and/or outputs of the magnetic head, such as amplifying a weak signal which is read by the magneto-resistive head.
Because the head slider floats from the hard disk which rotates at the high speed by a distance of the sub-μm order, it is desirable to prevent foreign particles such as dust particles and the like from adhering to the hard disk and the head slider, since the foreign particles will cause the so-called head crash.
Therefore, there are demands to make the head assembly have a structure that will not easily generate foreign particles.
2. Description of the Related Art
FIG. 1A is a perspective view showing a conventional head assembly, and FIG. 1B is a cross sectional view showing an encircled part A of the head assembly shown in FIG. 1A.
In a head assembly 10 shown in FIG. 1A, a head slider 20 is mounted on a gimbal part 12 which is provided on a tip end of a suspension 11. As shown in FIG. 1B, a head IC chip 30 is mounted face-dawn in a head IC chip mounting part 15 which is located at a central part of the suspension 11. The head IC chip 30 is a bare chip, such that a main chip body 31 which is made of silicon is exposed.
Materials such as silicon and GaAs which are generally used for a base substrate of the head IC chip 30 are fragile and easily crack or chip, because such materials have crystal orientation and have a high elasticity modulus which makes such materials hard. Accordingly, the chip generates the foreign particles (or powder) when an external force is applied thereon, such as when dicing the wafer to the chip size, when handling the chip to mount the chip, and due to ultrasonic bonding stress generated when mounting the chip.
Even if the head IC 30 is cleaned at a latter process, it is still impossible to remove extremely small foreign particles on the order of 1 μm or less, for example. In addition, additional foreign particles may be generated during the cleaning process.
Therefore, when the residual foreign particles scatter from the head IC chip 30 due to vibration or air flow caused by the operation of the disk unit, the foreign particles may cause the head crash, thereby deteriorating the reliability of the disk unit.